The biocompatibility of biofuel cells operating inside the body

In 1968 Wolfson et al. published the concept for producing energy inside the body using catalytic electrodes exposed to the body fluid as an electrolyte and utilising naturally occurring fuels such as glucose. Since then, the technology has advanced to enhance the levels of power using enzymes immobilised within three-dimensional bioelectrodes that are nanostructured. Current research in the field of enzymatic fuel cells is directed toward applying electrochemical and nanostructural expertise to increase the energy density, to increase the power density, to increase the operational stability, and to increase the voltage output. Nonetheless, biocompatibility remains the major challenge for increasing the life-time for implanted enzymatic biofuel cells. Here, we discuss the current issues for biocompatibility and suggest directions to enhance the design of biofuel cells so as to increase the life-time of implantation whilst maintaining sufficient performance to provide power for implanted medical devices.